1. Field of the Invention
The invention relates to additives useful for reducing metal corrosion and methods of employing same. The invention particularly relates to additives useful for reducing metal corrosion in systems having an alkaline pH and methods of employing same.
2. Background of the Art
The following discussion is provided solely to assist the understanding of the reader, and does not constitute an admission that any of the information discussed or references cited constitute prior art to the present invention.
CO2 is a greenhouse gas that that is believed to contribute to the phenomena known as global warming. In 2005 there were 25 billion metric tons of anthropogenic CO2 released into the atmosphere, approximately one third of that was from the combustion of coal for the production of electricity. It would be desirable in the art of employing fossil fuels to capture and sequester CO2.
It follows then, that coal-fired power plants represent a logical place to begin emission reduction strategies, as they contribute significant point source emissions. Some strategies include but are not limited to underground storage in geological formations or oil and gas depleted sites, biological fixation of CO2 to plant material, and chemical conversion to water-soluble or water-insoluble mineral carbonates. Strategies of burying CO2 are commonly referred to as carbon dioxide sequestration. However, conversion of CO2 into mineral carbonates that can be used for industrial applications, such as building materials, can be referred to as carbon dioxide transformation since the carbon dioxide is reused for other anthropogenic purposes.
At least some known carbon separation technologies intervene at different points in coal (and/or natural gas) systems. For example, carbon separation technologies that separate CO2 from combustion flue gases are generally known as post-combustion carbon separation technologies. Known post-combustion carbon separation technologies include processes such as, but not limited to, physical absorption, cryogenic separation, solid sorbent separation, chemical looping combustion, chemical absorption, and/or membrane separation.
Some known chemical absorption processes attempt to remove CO2 from other combustion gases by an exothermic reaction of CO2 with separation solvents, for example, potassium carbonate, sodium hydroxide, and amine-based solvents. Known amine-based liquids may include alkanol amines, for example, diethanolamine, triethanolamine, activated methyl diethanolamine, and monoethanolamines (MEA). Use of amino acids is also known. During a known chemical absorption process, for example, a flue gas and an amine-based liquid such as MEA counter-currently flow within an absorber (scrubber). The flue gas may enter the scrubber near a bottom end, flow upward, and exit near an opposing top end. The liquid may enter the scrubber near the top end, flow downward, and exit near the bottom end.